1. Field of the Invention
The present invention relates to transfer apparatuses, transfer network systems, and transfer methods, and more particularly, to a transfer apparatus, a transfer network system, and a transfer method that are provided with a function to disclose data to a plurality of uses at the same time.
2. Description of the Related Art
Information transfer with the use of transfer networks, such as the Internet and leased lines, has been widely used in recent years also in economic activities including commerce. When important data is disclosed to users, such as news that can affect economic activities and an authentication key used to start a transaction, it is demanded that the differences in data disclosure time among users be reduced to increase fairness.
Methods aiming at simultaneous data disclosure in conventional general transfer networks include a method for distributing data simultaneously at certain time from a server in push technology service. It is not fair, however, because the time when each user receives the data greatly differs depending on the congestion states of transfer networks. In pull technology service, which discloses data in response to a request sent from a user, a method is used in which a server is made available to respond to a data disclosure request at certain time. It is advantageous, however, for a user closer to the server and using a larger-capacity transfer network because the user can perform more request trials within a given period of time.
A technology for reducing the differences in data disclosure time among users is disclosed in Japanese Unexamined Patent Application Publication No. 2000-187629 (Patent literature 1). This publication discloses in its abstract “Object: To provide a data distribution service that strictly guarantees a data transfer time for each user. Solving means: A distribution side formed of an IP server W and a gateway server GWS, or formed of a gateway server GWS only transmits an electronic mail in which the text is associated with the transfer time when the text is transferred to the transmission destination user; and a mobile terminal MS at the receiving side receives the text and the transfer time sent from the distribution side and controls the start of processing for the text (for example, display processing of the text) according to the transfer time and the current time. With this configuration, control is possible at the receiving side such that the processing for the text is not performed until the transfer time or the processing for the text is started at the transfer time.”
Another technology is disclosed in Japanese Unexamined Patent Application Publication No. 2006-74109 (Patent literature 2). This publication discloses in its abstract “Object: To eliminate unfairness among users by disclosing data simultaneously to users with the use of general-purpose hardware, software, and networks. Solving means: An additional software execution section 103 is provided between a browser 106 and a network 107. The additional software execution section 103 includes an additional software internal timer function section 104 and establishes first and second unicast connections 108 and 109 with a server 101. The additional software execution section transmits a data distribution request from the browser to the server at a predetermined time (152); receives distribution data from the server through the first unicast connection and temporarily stores the distribution data (154); sets a server time and a distribution data disclosure time sent from the server through the second unicast connection, in the additional software internal timer function section (154); and sends the distribution data to the browser at the set disclosure time (155).
The Network Time Protocol (NTP) and the Precision Time Protocol (PTP) version 2 in IEEE 1588 are known as technologies for synchronizing the time of apparatuses in a transfer network. Either of the technologies stipulates a time synchronization system between a server that provides a stable time and a client that follows the server time. The time synchronization precision depends on implementation systems, but it is said that the NTP provides millisecond order precision and the PTP version 2 in IEEE 1588 provides microsecond order precision.